1. Field of the Invention
The present invention relates to a direction-estimating device of a vehicle for estimating the direction of the vehicle based upon: the position of the vehicle calculated based upon signals from artificial satellites; and a planning route set on a map or the like, and a driving control device including the aforementioned direction-estimating device.
2. Description of the Related Art
In recent years, navigation devices are widely used for vehicles, which employ a Global Positioning System (GPS) for detecting the position of the vehicle based upon the position data received from artificial satellites. Furthermore, various techniques have been proposed and put into practical use, wherein driving of the vehicle is controlled based upon the vehicle-position information obtained by the GPS.
For example, a device is disclosed in Japanese Unexamined Patent Application Publication No. 2003-26017, wherein the position of the vehicle is calculated based upon information from the GPS, a planning route along which the vehicle is to be driven is calculated, and the viewing distance is computed based upon the steering-frequency response. With the aforementioned automatic steering technique, the future-position lateral deviation of the vehicle corresponding to the viewing-distance point from the planning route is computed based upon the moving vector of the vehicle, and the current-position lateral deviation of the vehicle from the planning route is computed. Subsequently, the target amount-of-change of steering angle is computed based upon the aforementioned current-position lateral deviation and future-position lateral deviation for steering such that the vehicle follows the planning route, whereby steering is made according to the command value determined based upon the computed target amount-of-change of steering angle.
With such a technique as disclosed in the aforementioned Japanese Unexamined Patent Application Publication No. 2003-26017, the future-position lateral deviation is computed based upon the moving vector of the vehicle. Accordingly, the moving vector of the vehicle calculated with inaccuracy leads to the future-position lateral deviation with insufficient precision, resulting in automatic steering with insufficient precision.
The present invention has been made in order to solve the aforementioned problems, and accordingly, it is an object thereof to provide a direction-estimating device for precisely estimating the direction of the vehicle appropriately corresponding to each driving situation, and a driving-control device including the aforementioned direction-estimating device, thereby enabling precise and stable control of driving of the vehicle.